1. Field of the Invention
The present invention relates to audio equipment. More particularly, the present invention relates to a fast-acting excursion limiter for use with audio equipment and operable to limit movement of speakers to prevent damage and sound distortion.
2. Description of Prior Art
Speakers produce audible sound though physical movement of a cone. This movement is commonly referred to as excursion. Excessive excursion often causes a cone to impact other components of speakers, especially when operating at high output levels and low frequencies. This impact frequently damages speakers and causes severe distortion.
Currently, there are four methods for preventing excessive excursion. A first method is to simply avoid operation at high output levels. However, excursion can differ depending upon how many speakers are being used and how those speakers are connected. Additionally, many users simply wish to operate their audio systems at high output levels.
A second method is to broadly attenuate audio signals at low frequencies. However, many users enjoy high output levels at low frequencies. Thus, attenuating audio signals at all low frequencies prevents users from fully enjoying their audio systems.
A third method is to clip audio signals at output levels below that expected to cause excessive excursion. However, clipping audio signals produces discontinuities and severe distortion. This distortion again prevents users from fully enjoying their audio systems.
A forth method is to sense a voltage or a current supplied to speakers and, through a corrective feedback circuit, attenuate audio signals supplied to speakers. However, feedback circuits inherently have delayed reactions and cannot react quickly enough to prevent excessive excursion. Users therefore must currently choose between operating their audio systems at their optimal levels and risking the effects of excessive excursion or using one of the existing methods of limiting excursion and settling for lower performance associated therewith.
Accordingly, there is a need for an improved excursion limiter that overcomes the limitations of the prior art.